Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board A65 Clutch Cush Drive Screws Loosening

The 3 cush drive screws in the back of the cush drive on my A65 keep coming loose, has anyone had this problem before and fixed it? I am thinking using loctite red and staking the screw heads to the inner clutch backing plate. Were these screws staked in place at the factory? (The cush drive is the hub in the center of the clutch)

Thank you in advance

I believe they were staked, a punch into the screw drive slot. Later (T140 maybe?) they used through bolts.

I am looking at other parts in the clutch and in the area of the clutch to check for damaged and loose parts.

Blue locktite
They were notorious for doing this back in the day then the spider would chew through the side plates

Thanks for this information BSA_WM20. I was thinking of using red loctite but blue could be a better choice.

Why not stake them? Then you'll KNOW they won't come loose.

They were staked from the factory. I would tell you what sort of punch to use, but the first word gets deleted by the web moderator.
And, yes the later ones used bolts in place of those screws.

Most shock absorbers with any mileage on them are worn beyond repair anyway, so I usually replace the whole unit. It's a poorly engineered piece of kit to be honest.
In the very few cases I re-use the screws I use Loctite and stake them too.

SR

David, does the deleted word begin with a "P" and end with "K" ?

The moderator probably won't allow the name of a certain class of metal file, either, because it begins with a "B" and ends with "RD."

Thank you; I didn't get that.

Stein Roger, are you saying that you replace the entire clutch center hub?

I would reccomend replacing the whole hub , every bit of it wears, the grooves get notched and the spider wears out against the rear plate, they re not worth rebuilding as the cost of the individual parts comes to more than a complete unit. They are a high wear item, because the wear is hidden it goes largely unnoticed until no amount of new plates or springs will prevent it from sipping and dragging as the worn spider allows the drum to tilt under load, the more worn it gets the faster it gets worse. A worn hub will end up causing slip and drag , this cooks the clutch up and the plain steels warp, after that its a nightmare of positive wear feedback.

Precisely! There's probably a proper British term for such a punch but I don't know it.

That would be "centre punch"

+1, the individual parts alone would buy you a new complete hub and a night on the beer, it just isn't worth messing with an old one.

I'm just re-assembling clutch centre now. Before removal, I understood that the plates were fastened with 6 x 1 BA screws, but mine has the later 3 bolts which are 1 3/8" BSF (or cycle) x 1/4", both being 26 TPI. The ends are slotted then staked, I had to drill off the ends to remove the the bolts as I wanted to check the rubbers. New bolts just need a saw cut on the end, Loctite then staking. All the parts lists I've seen just show the original 6 CSK screws.

Correction, the bolts are actually 1/4" UNF, 28 TPI.

I think this came out with the later triumphs but it was a good modification for all bikes. the screws should be 1/4 UNF. a spot of weld and ground back wouldn't go a miss.

I think this came out with the later triumphs but it was a good modification for all bikes. the screws should be 1/4 UNF. a spot of weld and ground back wouldn't go a miss.[/quote]

You are correct Allan, I've just measured them, they're 28 TPI UNF. What threw me was the bolt heads are stamped GSF, the G looking more of a B!

I'll alter previous thread.

Over here a center punch is usually a blunt instrument with a flat, circular end. A pr**k punch has a sharp end.

how come ball cock and gland nut go through unchecked?

I have heard that this problem was corrected on later models with larger bolts or through bolts. What year was this and will it fit a 69 A65L?

It was on the later post 73 triumphs I believe and yes it will fit on any 3 spring A65 clutch.

So would this is a direct swap without changing any other parts?

Yes, take the old cush drive out and put the new one in....

Obviously replace anything else that needs replacing. But wouldn't wouldn't waste my time repairing them anymore, spent too long doing that.

I believe any new (reproduction) cush drive will have through bolts, so you don't have to worry about specifying 73-or-later triumph. Just order the entire assembly as one part and it will come with the bolts in place.

p/n 57-4435

I installed a center hub that has through bolts, I have done this same repair before and with the through bolts most likely it will not need to be done again.

With the clutch lever pulled in all the way in first gear it now just barely creeps forward. The screw in the center of the clutch was adjusted all the way in and then out between 1/2 to 3/4 turn with the clutch cable unhooked from the clutch hand lever. This could be another post.

Thank you for the replies.

are you using the factory pressure plate or an aftermarket one (say from SRM)? the factory pressure plate uses a finer thread to the aftermarket ones (I think the SRM is UNC from memory), if it is the aftermarket one you will want to back the screw off by 1/8th-1/4 turn as anything much above this will not give enough lift and cause the bike to creep when the clutch is pulled in.

Examples of common punches from a US catalogue https://engineeringlearn.com/types-...king-principle-advantages-disadvantages/

Although I haven't heard of the name "p***k" punch before.

I have always run factory pressure plates on my A65s and I found that the "1/2 to 3/4-turn out" spec in my Chilton manual was too much, would cause the clutch to drag, particularly when warm. I've always attributed this to the clutch discs swelling. I believe the OE discs, which were on my '67 L when I got it, but only for a short amount of time, did not swell to the same degree as the aftermarket cork discs. This could explain the seemingly erroneous adjustment spec in the books, but this is only a theory based on a sample of ONE.

Also, the adjuster nuts need quite a bit of fine tweaking in order to get the pressure plate moving back and forth evenly.

One of my adjuster nuts was locking up on the spring, so I reversed (the spring) and it cured that problem. I noticed somewhere that some had filed off the indentations on the nuts, but not sure whether that's a good idea.

Some things that cause clutch drag.

Pressure plate spring pressure imbalance. Correct by adjusting spring pressure,

Warped steel plates.Replace plates warped by 3thou or more.

Worn cush drive. Replace with new unit.

Primary chain missaligned, check shims behind sprocket.

Clutch centre adjuster fouling with inspection cap at full lift, either shorten push rod or fit a thick O ring to the capto move it out.

Any single item above or combo will cause the machine to creep with the clutch held in.

A good list, but I found that checking the primary chain/sprocket alignment to any fine degree is problemati.c

The clutch did not creep before this repair. The adjusting screw is 3/4 turn out. The pressure plate was not changed and should be stock. It does work okay, but it just creeps forward very slightly at a standstill when running in 1st gear and the clutch pulled in all the way.

Straight edge, easier with the bike over on it's side.or before engine fitted.

Possibly the pressure plate is lifting unevenly,please note that the spring pressure adjusters must be operated in whole turns,( This is because the adjuster nuts have locking pips, if the spring is not seated against the pip it will turn in use until it is seated) start with the adjuster threads level with the nuts, operate the clutch and note any uneven lift, adjust the spring pressure to give even lift all round, dont worry if the thread protrude or recess unevenly , so long s the plate lifts even and clean all round it is good to go. If you have trouble turning the pressure adjusters because of the pips use the tip of a butter knife to ease the spring past the pip.

If the clutch isn't disengaging, I would start by looking at the cable adjustment and whether the lever (or ball lifter) in the timing cover is adjusted properly and has the ball bearing in place which bears against the pushrod.

When you rebuilt the clutch center, you probably removed the clutch push-rod from the left side, the clutch lift mechanism on the TS has a ball bearing, which bears against the clutch push-rod. It would be worth checking if the ball bearing is still in place or not. If its missing you will have inadvertently shortened the push-rod hence the clutch cant fully disengage.

If the ball bearing is in place, the way I adjust the clutch is as follows (note, others may have their own ideas, this is just mine):-
- as a starting point, make sure all the springs are the same length and also the spring cups have the same depth. Its not unusual to find mismatched parts here.
- with the adjuster on the pressure plate undone, start with adjusting the cable so that when the handle bar lever is pulled in, the lever mechanism in the timing cover is fully pulled in, but not fouling or grounding on any parts of the cover.
- screw in the clutch springs as far as they will go and then unscrew each by an equal amount (e.g. 1 turn), these settings will later be used to check if the clutch needs more free play to disengage
- turn in the adjuster screw on the pressure plate so its just touching the pushrod, then back off by 1/2 a turn
- pull the handlebar lever and try kicking over, ideally the clutch plates should disengage
- if the clutch plates dont fully disengage try unscrewing the springs all by 1/2 turn and see if its any better.

You should arrive at a point where the clutch disengages enough and doesn't drag but also doesnt slip when running.

I think the ball bearing at the end of the clutch rod is 7/32", I always seem to lose mine somehow when taking out the push-rod and I've temporarily replaced with a 3/16" ball which I had.

3/4 turn out is too much. Try 1/4 turn out. And adjust it when it's warm.

I noticed that the adjusting screw in the center of the pressure plate looks to be too far into the locknut. After noticing this I removed the adjusting screw and pulled out the rod. The rod looks okay on both ends, there doesn’t look to be any wear on it so I would think that it is okay.

Any suggestions about the adjusting screw being too far in?


At this point I also want to adjust the 3 screws on the pressure plate so that it rotates evenly.

Any tips on adjusting the 3 spring screws so that the pressure plate rotates evenly?

If the centre screw is too far in then when you adjust it, it will be adjusting against the main shaft and not the push rod. The pushrod should be poking though by a few mm when there is no tension on the cable, so push against the rod and see if it is still proud. Following that, as long as the nut is fully On the adjustment grub screw then all should be ok.

For clutch adjustment, start off with all the screws with the top of the heads flush with the screw tops. Then push against the plates and check the gap behind them. Adjust the adjusting screws in or out until there is an even gap all round.

Before you do, check all the spring cups are the same length and if possible, check the springs also, if you don’t know the history of the springs, get some new ones from a reputable supplier.